ISLAMABAD, Pakistan (CNN) -- Pakistan understands the need to move "urgently and transparently" against extremists on its soil after last week's terrorist attacks in India, U.S. Secretary of State Condoleezza Rice said after meetings with Pakistani leaders.

"I found a Pakistani government that's focused on the threat and understands its responsibility to respond to terrorism and extremism wherever it is found," Rice told reporters Thursday after sessions with the country's president and prime minister.

After the talks, Pakistani President Asif Ali Zardari pledged to assist in the investigation and move against "any Pakistani elements found involved in the attack," his office said.

Rice landed in Islamabad in an effort to ease tensions between India and Pakistan following the terrorist attacks in India's financial capital Mumbai.

Indian authorities have said the gunmen who killed nearly 180 people came from Pakistan, but Pakistan has blamed "non-state actors" for the attacks.

Rice said the discussions focused on the attacks and what she called Pakistan's obligation "to deal with those who may use Pakistani territory, even if they are non-state actors."

"There does need to be action," she said. "There needs to be action urgently and transparently. And it's a message that has been well-received in Pakistan, because it's Pakistan's fight as well."

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Pakistan is a U.S. ally in the battle against the Taliban and al Qaeda in Afghanistan -- a conflict that has spread into northwestern Pakistan. Rice's visit to Islamabad came a day after Adm. Mike Mullen, the chairman of the U.S. Joint Chiefs of Staff, met with Zardari and top military and intelligence officials in Islamabad.

India has said a Pakistan-based Islamic militant group with ties to al Qaeda helped plot the Mumbai attacks and says the sole surviving attacker is a Pakistani national. The group, Lashkar-e-Tayyiba, is the same one New Delhi accused of carrying out a 2001 attack on its parliament that brought the South Asian nuclear powers to the brink of war. Watch claims attackers came from Pakistan »

India has demanded Pakistan hand over a group of wanted terrorist suspects. Its foreign minister, Pranab Mukherjee, warned that India will consider all options "to protect its territorial integrity" if Pakistan refuses.

"So far as the government of India is concerned, what action will be taken by government will depend on the response we have from Pakistan authorities," Mukherjee said.

Rice met with Mukherjee on Wednesday. While she said Pakistan needs to cooperate with the investigation into the Mumbai massacre, she warned India that "any response needs to be judged by its effectiveness in prevention, and also by not creating other unintended consequences or difficulties."

U.S. Joint Chiefs Chairman Adm. Mike Mullen warned Thursday of the "increasingly sophisticated threat of militant extremism in South Asia," and urged India and Pakistan to collaborate against a common enemy.

America's top military officer is in New Delhi, for talks with senior Indian civilian and military leaders.

According to a statement issued by Mullen's Pentagon office, the admiral thanked Indian officials "for their restraint and their desire to cooperate with Pakistani officials" and repeated an offer by U.S. Secretary of State Condoleezza Rice to help in the investigation of the Mumbai attacks which killed 179 people.